Surgical device for clamping, ligating, and severing tissue

ABSTRACT

A surgical device for severing tissue, the surgical device comprising; a first shaft having a first internal lumen and a first slot disposed at a distal end; a clamp slidingly disposed in the first slot between open and closed positions to capture tissue in the first slot, the clamp having a clamping surface disposed at a distal end; at least one electrode for applying RF energy to the tissue captured in the first slot; a cutting blade slidingly disposed in the first slot between open and closed positions, the cutting blade having a cutting edge to sever the tissue; first actuation means for actuating the clamp between the open and closed positions; and second actuation means for actuating the cutting blade between the open and closed positions.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to surgical devices, andmore particularly, to a surgical device for clamping, ligating, andsevering tissue, preferably, a side branch of a vessel to be harvested.

[0003] 2. Prior Art

[0004] Both saphenous veins and radial arteries are used as conduits incoronary artery bypass surgery. Conventional techniques for harvestingthese vessels involve an incision length approximately equal to thelength of the vessel being harvested. Recently, various bipolarendoscopic vessel-harvesting devices have been developed as a means ofremoving saphenous veins or radial arteries in a minimally invasivemanner.

[0005] Users of theses devices frequently struggle to separate sidebranches of the veins or arteries when said side branches run beneath orabove the main trunk of the vessel. In addition, the visualization ofthe vessel may be lost in excess adipose tissue. Finally, the userfriendliness of these devices is subject to question since the stepsinvolved in identifying, securing, and dissection/ligation of sidebranches is not always intuitive, i.e., the user frequently has toconcentrate on what his or her hands are doing and not the vessel athand. Current bipolar devices also fail to complete the terminalligation required to excise the vein or artery.

[0006] Others have attempted to harvest vessels via endoscopic means byseveral methods. One method involves use of scissors and ligating clips.Two tools are required for this approach, thus complicating theprocedure by excess tool exchanges. Furthermore, the placed clips canhinder subsequent movement of instruments. Finally, foreign bodies(clips) are left in the patient's limb.

[0007] Another approach involves the use of a knife placed between twowire guides that are capable of applying a current across the sidebranch. This design can potentially result in the spread of thermalenergy to the target vessel, potentially compromising its utility as aconduit for CABG surgery. Still yet another approach involves the use ofscissor-like clamping jaws that open around a side branch, and then mustbe closed, whereby a current is applied to the vessel within the jawsbefore the vessel is harvested. However, these types of instruments aredifficult to use in confined spaces because of the upward openingmovement of at least one of the jaws often causes an interference withobjects in the field. Further, the upward opening jaw obscures thevision of the surgeon using the device.

SUMMARY OF TRE INVENTION

[0008] Therefore it is an object of the present invention to provide asurgical device for clamping, ligating, and severing tissue, which isfriendlier to use than the devices of the prior art.

[0009] It is another object of the present invention to provide asurgical device for clamping, ligating, and severing tissue, whicheliminates the need for ligating clips to ligate side branches of avessel being harvested.

[0010] It is yet another object of the present invention to provide asurgical device for clamping, ligating, and severing tissue which limitsthe spread of thermal energy so as not to compromise the utility of thevessel to be harvested.

[0011] It is yet another object of the present invention to provide asurgical device for clamping, ligating, and severing tissue whicheliminates the necessity of opening and closing scissor-like jaws.

[0012] It is still yet another object of the present invention toprovide a surgical device for clamping, ligating, and severing tissue,which minimizes the need for multiple instrument exchanges needed toharvest a vessel.

[0013] Accordingly, a surgical device for severing tissue is provided.The surgical device comprising; a first shaft having a first internallumen and a first slot disposed at a distal end; a clamp slidinglydisposed in the first slot between open and closed positions to capturetissue in the first slot, the clamp having a clamping surface disposedat a distal end; at least one electrode for applying RF energy to thetissue captured in the first slot; a cutting blade slidingly disposed inthe first slot between open and closed positions, the cutting bladehaving a cutting edge to sever the tissue; first actuation means foractuating the clamp between the open and closed positions; and secondactuation means for actuating the cutting blade between the open andclosed positions. The tissue is preferably a side branch of a vesselbeing harvested. Preferably, the first shaft is disposed at a proximalend to a handle.

[0014] The surgical device preferably further comprising a dissectiontip disposed at the distal end of the first shaft for dissecting tissue.

[0015] The clamp preferably comprises a second shaft having a secondinternal lumen, the second shaft being slidingly disposed in the firstlumen. More preferably, the second shaft has a second slot at the distalend, wherein the second slot divides the clamping surface into twoprongs. The cutting blade is preferably slidingly disposed in the secondinternal lumen of the second shaft. Preferably; the at least oneelectrode comprises first and second electrodes, each of a differentpolarity. More preferably, the first electrode comprises at least theclamping surface of the clamp and the second electrode comprises atleast the cutting edge of the cutting blade. Alternatively, the firstelectrode comprises at least the clamping surface of the clamp and atleast the cutting edge of the cutting blade and the second electrodecomprises at least a portion of the first shaft. The at least a portionof the first shaft preferably comprises an edge defining the first slotin the first shaft.

[0016] Preferably, the first actuation means comprises a button movablydisposed in a handle and operatively connected to the clamp, whereinmoving the button moves the clamp between the open and closed positions.The second actuation means preferably comprises a button movablydisposed in a handle and operatively connected to the cutting blade,wherein moving the button moves the cutting blade between the open andclosed positions. More preferably, the first and second actuation meanscomprises a button movably disposed in a handle and operativelyconnected to the clamp and cutting blade, wherein moving the button afirst predetermined amount moves the clamp between the open and closedpositions and moving the button a second predetermined amount furthermoves' the cutting blade between the open and closed positions.

[0017] Also provided is a method for severing tissue with the surgicaldevices of the present invention. The method comprising: capturingtissue in the first slot; sliding the clamp in the first slot to clampthe tissue in the first slot; applying RF energy to the at least oneelectrode to cauterize the tissue; sliding the cutting blade in thefirst slot to sever the cauterized tissue. The tissue is preferably aside branch of a vessel to be harvested.

[0018] The method preferably further comprising dissecting tissue fromthe vessel to be harvested. Preferably, the first actuation meanscomprises a button movably disposed in a handle and operativelyconnected to the clamp, the method further comprising moving the buttonto move the clamp between the open and closed positions. Preferably, thesecond actuation means comprises a button movably disposed in a handleand operatively connected to the cutting blade, the method furthercomprising moving the button to move the cutting blade between the openand closed positions. More preferably, the first and second actuationmeans comprises a button movably disposed in a handle and operativelyconnected to the clamp and cutting blade, the method further comprisingmoving the button a first predetermined amount to move the clamp betweenthe open and closed positions and moving the button a secondpredetermined amount to further move the cutting blade between the openand closed positions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] These and other features, aspects, and advantages of theapparatus and methods of the present invention will become betterunderstood with regard to the following description, appended claims,and accompanying drawings where:

[0020]FIG. 1 illustrates an isometric view of a preferred implementationof a surgical device of the present invention.

[0021]FIG. 2 illustrates an enlarged view of the distal end of thesurgical device of FIG. 1.

[0022]FIG. 3 illustrates the distal end of FIG. 2, wherein a vessel incaptured in a slot of the surgical device.

[0023]FIG. 4 illustrates the distal end of FIG. 2 with a cutting bladepartially extended into the slot.

[0024]FIG. 5 illustrates the distal end of FIG. 2 with the cutting bladeextended fully through the slot.

[0025]FIGS. 6A, 6b, and 6 c illustrate the distal end of FIG. 2 withalternative dissection tips.

[0026]FIG. 7 illustrates a sectional view of the surgical device takenalong line 7-7 of FIG. 1.

[0027]FIG. 8 illustrates a sectional view taken along line 8-8 of FIG.7.

[0028]FIG. 9 illustrates a variation of the surgical device of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0029] Although this invention is applicable to numerous and varioustypes of tissue to be severed, it has been found particularly useful inthe environment of severing vessels such as side branches of a bloodvessel being harvested. Therefore, without limiting the applicability ofthe invention to severing vessels such as side branches of a bloodvessel being harvested, the invention will be described in suchenvironment. Furthermore, the surgical devices of the present inventionare preferably configured as disposable devices, however, the surgicaldevices can also be configured as semi-reusable or reusable withoutdeparting from the scope or spirit of the present invention.

[0030] Referring now to FIGS. 1 and 7, a surgical device is illustratedtherein, generally being referred to by reference numeral 100. Thesurgical device 100 has a housing 102, also serving as, andalternatively referred to as a handle. The handle 102 is generallyfabricated from a medical grade thermoplastic and is preferably formedin a “clamshell” design having first and second halves 102 a, 102 b. Theclamshell design allows for easy assembly of the internal components.The halves 102 a, 102 b are fixed together by any means known in theart, such as by a press fit or with a medical grade epoxy.

[0031] The surgical device 100 further has a first shaft 104 having afirst internal lumen 104 a. The first shaft is fabricated from a medicalgrade resilient material such as stainless steel and preferably has aproximal end 104 b affixed to a distal end 102 c of the handle 102 byany means known in the art such as a press fit or with a medical gradeepoxy.

[0032] Referring now to FIGS. 1-3, a slot 106 is disposed at a distalend 104 c of the first shaft 104. The slot 106 is preferably formed byremoving material from a cross-sectional portion of the first shaft 104such that the slot 106 has a peripheral edge 106 a defining theboundaries of the slot 106. The removal of material to form the slot 106can be done by conventional machining or punching processes known in theart. The slot 106 is shown encompassing a large portion of thecross-section of the first shaft 104 so as to accommodate the largestsize tissue 101 possible for a given diameter first shaft 106.

[0033] The surgical device 100 further includes a clamp 108 slidinglydisposed in the slot 106 between open and closed positions to capturetissue 101, such as a vessel, in the slot 106. As discussed above, thevessel is preferably a side branch 101 of a vessel 103 to be harvested.The clamp 108 further has a clamping surface 108 a disposed at a distalend of the clamp 108′. In the open position, the clamp 108 does notsubstantially interfere with the capturing of tissue in the slot 106,while in the closed position, the clamp 108 captures tissue between theclamping surface 108 a and at least a portion of the slot edge 106 a,preferably a distal portion of the slot edge 106 a.

[0034] Preferably, the clamp 108 comprises a second shaft 110 having asecond internal lumen 110 a. The second shaft 110 is slidingly disposedin the first lumen 104 a of the first shaft 104. The second shaft 110 ispreferably a resilient medical grade material such as stainless steeland preferably a loose running fit is maintained between the first shaft104 and the second shaft 110. Alternatively, a spacer (not shown) can beprovided between the first shaft 104 and the second shaft 110, to definean annular space (not shown) between the first shaft 104 and the secondshaft 110. The spacer is preferably a polymer. The polymer spacer canalso act as a dielectric insulator. Still more preferably, the secondshaft 110 has a slot 112 extending axially from a distal end 111 of thesecond shaft 110. Preferably, the slot 112 divides the clamping surface108 a into two discrete portions or prongs 112 a, 112 b.

[0035] Referring now to FIGS. 4, 5, and 7, the surgical device 100 alsohas a cutting blade 114 slidingly disposed in the first slot 106 betweenopen and closed positions. The cutting blade 114 preferably has asharpened leading cutting edge 114 a. In the open position, the cuttingblade 108 does not substantially interfere with the capturing of tissuein the slot 106, while in the closed position, the cutting blade 114severs the captured tissue between the clamping surface 108 a and atleast a portion of the slot edge 106 a.

[0036] The cutting blade 114 is preferably at a distal end of a thirdshaft 116, which is slidingly disposed in the second internal lumen 110a of the second shaft 110. The third shaft 116 is preferably a resilientmedical grade material such as heat-treatable stainless steel andpreferably a loose running fit is maintained between the third shaft 116and the second shaft 110. Alternatively, a spacer (not shown) can beprovided between the third shaft 116 and the second shaft 110 to definean annular space (not shown) between the second shaft 110 and the thirdshaft 116. The spacer is preferably a polymer. The polymer spacer canalso act as a dielectric insulator. At least the cutting edge 114 a ofthe cutting blade 114 is preferably heat treated to maintain a sharpedge for the expected life of the surgical device 100.

[0037] At least one electrode is provided on the surgical device 100 forapplying RF energy to the tissue captured in the slot 106. Preferably,the surgical device 100 is configured to apply RF energy to cauterizethe captured tissue and more preferably the surgical device 100 isfurther configured as a bipolar device. However, the preferable meansfor cauterization is given by way of example only and not to limit thescope or spirit of the present invention. For instance, the surgicaldevice 100 can be used in a monopolar configuration in combination witha grounding plate as is known in the art. Furthermore, the surgicaldevice 100 can be configured to apply sonic energy to cauterize thecaptured tissue.

[0038] In the preferred bipolar configuration, the at least oneelectrode comprises first and second electrodes, each of a differentpolarity. Preferably, the first electrode comprises at least theclamping surface 108 a of the clamp 108 and the second electrodecomprises at least the cutting edge 114 a of the cutting blade 114.Alternatively, the first electrode comprises at least the clampingsurface 108 a of the clamp 108 and at least the cutting edge 114 a ofthe cutting blade 114 and the second electrode comprises at least aportion of the first shaft 104. In the alternative configuration, the atleast a portion of the first shaft 104 comprises the edge 106 a definingthe slot 106.

[0039] The RF energy is preferably supplied from an electrosurgicalgenerator (not shown), as is known in the art. The electrosurgicalgenerator supplies the RF energy to the respective electrodes via wires118, 120. The wires 118, 120 are preferably routed through the handle102 and electrically coupled, such as by soldering, to the respectiveelectrodes. A switch (not shown) is also preferably provided forenergizing the electrodes with RF energy from the electrosurgicalgenerator. The switch (not shown) can be provided in the handle 102 orin a foot switch as are known in the art.

[0040] In either bipolar configuration, surfaces such as the exterior ofthe first, second, and/or third shafts 102, 110, 116 must be coated witha dielectric material to prevent a short between the electrodes ofdifferent polarity and also to prevent accidental cauterization ofunintended tissue. Such coatings are well known in the art, such aspolytetrafluorethylene (PTFE). It is important to note, that because theelectrodes are offset from one another, thermal spread to unintendedportions of the tissue or vessel being cauterized is minimized.

[0041] Referring now to FIGS. 7 and 8, the surgical device 100 alsoincludes first actuation means for actuating the clamp 108 between theopen and closed positions. In addition to the first actuation means, thesurgical device 100 further includes second actuation means foractuating the cutting blade 114 between the open and closed positions.Preferably, the first and second actuation means are provided byactuation of a single button 200 movably disposed in the handle 102. Thebutton 200 is preferably movably disposed in the handle 102 andoperatively connected to both the clamp 108 and cutting blade 114,wherein moving the button 200 a first predetermined amount moves theclamp 108 between the open and closed positions and moving the button200 a second predetermined amount further moves the cutting blade 114between the open and closed positions.

[0042] Preferably, the button 200 includes a button projection 202either integral with or separably attached to the button 200. The buttonprojection 202 is slidingly disposed in a slot 204 in the handle 102. Aportion of the button projection is disposed in a first slot 206 in aproximal end 110 b of the second shaft 110 and connected thereto,preferably by a pinned joint 208. The first slot preferably extends inthe axial direction from the distal-most end of the second shaft 110.Thus, since the button 200 and second shaft 110 are directly linked, adistal movement of the button 200 results in a corresponding distalmovement of the second shaft 110 and clamp 108 attached at a distal endthereof. The second shaft 110 can be biased in either of the closed oropen positions by way of a spring (not shown) disposed in the handle102.

[0043] The second shaft 110 preferably further has a second slot 210formed at the proximal end 110 b in a wall of the second shaft 110 andextending in the axial direction. Preferably, the second slot 210 isformed at two sides of the wall of the second shaft 110. The third shaft116 has a pin 212, either integrally formed or separably attached, at aproximal end 116 a of the third shaft. The pin is slidingly disposed ina distal end 210 a of the second slot 210 when the clamp 108 is in theopen position. Thus, as the button 200 is moved distally to move theclamp 108 towards the closed position, the pin 212 moves in the secondslot 210 from the distal end 210 a towards a proximal end 210 b of thesecond slot 210. However, during the movement of the pin 212 in thesecond slot 210, the third shaft 116 and the cutting blade 114 attachedthereto are stationary. When the pin 212 reaches the proximal end 210 bof the second slot 210, continued distal movement of the button 200causes the distal end 210 b of the second slot 210 to urge against thepin 212 to correspondingly move the third shaft 116 and the cuttingblade 114 attached thereto distally from the open to the closed positionto sever tissue captured in the clot 106 of the first shaft 104.

[0044] Preferably, a spring 211 is disposed in the second slot 210between the pin 212 and the proximal end 210 b of the second slot 210.The spring 211 ensures that the cutting blade 114 will not move into theslot 116 until the clamp 108 is fully through the slot 116. Furthermore,the spring constant of the spring 211 can be chosen such that asufficient clamping force must be reached before the cutting blade 114is advanced. This ensures a proper ligation of a vessel 101 captured inthe slot 106 before transection by the cutting edge 116 of the cuttingblade 114.

[0045] Alternatively, two buttons (not shown) can be provided, one ofwhich operates the actuation of the clamp 108 between the open andclosed positions and the other of which operates the actuation of thecutting blade 114 between the open and closed positions. Furthermore, aswitch (not shown) can be provided to apply the cauterization energy tothe electrodes automatically upon the completion of clamping of thetissue and subsequent to the cutting of the cauterized tissue.

[0046] Referring back to FIG. 2, the surgical device 100 also preferablyincludes a dissection tip 105 disposed at the distal end 104 c of thefirst shaft 104 for dissecting tissue. The dissection tip 105 ispreferably separably formed from the first shaft 104 and attached by anymeans known in the art such as by a press fit, medical grade epoxy, orbrazing. However, the dissection tip 105 can also be integrally formedwith the first shaft 104, such as by rolling the distal edge 104 c ofthe first shaft 104 into an appropriate shape. The dissection tip ispreferably shaped to facilitate the dissection of tissue and further hasa sloped leading edge 105 a for facilitating capturing of a vessel inthe slot 106. The dissection tip 105 further preferably has a slot 107formed therein for acceptance of a distal portion of the cutting blade114 as shown in FIG. 5. FIGS. 6A, 6B, and 6C illustrate alternativedissection tips 220, 230, 240, respectively.

[0047] Preferably, the surgical device further has a means (not shown)for evacuating smoke or other fluids from the body. Typically, theevacuating means comprises a vacuum port (not shown) such as a luerfitting disposed in the handle 102, which is in fluid communication withat least one of the lumens 104 a, 110 a of the first and second shafts104, 110 at one end and connected to a vacuum supply at another end.

[0048] Referring now to FIG. 9 where like numbers represent similarcomponents, a variation of the surgical device 100 is illustratedtherein. The variation of the surgical device being generally referredto by reference numeral 300. The surgical device 300 illustrated in FIG.9 is similar to the surgical device 100 illustrated in FIG. 1, but isparticularly configured for endoscopic vein harvesting.

[0049] The device 300 comprises a substantially similar instrument asdisclosed in FIGS. 1-5 and 7-8, with the exception that the housing 302is configured as is known in the art for blood vessel dissection andalthough surgical device 100 preferably includes a dissection tip 105,surgical device 300 includes a further dissection means 304 fordissecting tissue from a blood vessel to be harvested. The housing 302of surgical device 300 is pistol or L-shaped and has a handle portion306. The housing 302 also has a control portion 308 for placement of thebutton 200 as well being a housing for the remaining components of thefirst and second actuation means discussed previously with regard tosurgical device 100′.

[0050] The dissection means 304 preferably comprises a third shaft 310having an internal lumen for passage of an endoscope 312 therein. Theinternal lumen communicates with a lumen (not shown) in the handle andhas a hole 314 for insertion of the endoscope therein. The third shaft310 and the first shaft 104 are preferably arranged parallel to oneanother and each are connected at a proximal end to the control portion308 of the housing 302.

[0051] The dissection means 304 further has a substantially transparentheadpiece 316 shaped for dissecting tissue in proximity to the vessel103. Dissecting tissue about a vessel 103 with such a dissection means304 is well known in the art, such as that disclosed in U.S. Pat. No.6,206,823, the contents of which are incorporated herein by itsreference. In general, the headpiece 316 is advanced along the vessel103 to dissect the surrounding tissue from the vessel 103. Furthermore,a workspace is created between an interior surface 316 a of theheadpiece 316 and the vessel 103 for placement of the distal end 104 cof the first shaft 104. If a side branch 101 of the vessel 103 isencountered during the dissection (as viewed by the endoscope), the sameis ligated and dissected in the workspace using the clamp 108,electrodes, and cutting blade 114 as is described below.

[0052] A method for severing a side branch 101 of a vessel 103 using thesurgical devices 100, 300 of the present invention will now be describedwith reference to the Figures. A vessel 103 to be harvested is firstaccessed by making an incision, generally in the leg. Next,pre-dissection of an end of the vessel 103 is performed. Afterpre-dissection, the vessel 103 is traversed and dissected from thesurrounding tissue. The dissection of the surrounding tissue can beperformed with the dissection tip 105 and/or the dissection means 304.During the dissection of the vessel 103, whenever a side branch 101 isencountered, the device is positioned and advanced such that the sidebranch 101 rides up the inclined leading edge 105 a of the dissectiontip 105 until it falls into and is captured in the slot 106 as is shownby arrow A in FIG. 2.

[0053] Subsequent to capturing the side branch 101 in the slot 106, thebutton 200 is advanced distally to slide the clamp 108 in the slot 106to clamp the side branch 101 in the slot 106. Preferably, the sidebranch 101 is clamped between the clamping surface 108 a and a distalportion of the edge 106 a defining the slot 106. Once the side branch101 is captured, RF energy is preferably applied to the electrodes tocauterize the captured side branch 101. The cauterization of the sidebranch 101 sufficiently ligates the side branch 101 such that it can besafely severed. The side branch 101 is severed by continuing to advancethe button distally which results in the advancement of the cuttingblade distally through slot 106 and into slot 107 to sever thecauterized side branch 101. Those skilled in the art will appreciatethat because the ligation and transection of the captured tissue orvessel is performed in an open slot 106, visualization is greatlyimproved, even while the device 100, 300 is being advanced throughtissue.

[0054] Although, the devices 100, 300 are particularly useful forsevering side branches 101 of a vessel 103 to be harvested, they canalso be utilized in other procedures such as ligation of fallopian tubesfor fertility control, ligation and transection of bile ducts fornephrectomy, or for the transection of ligaments or other tissuestructures.

EXAMPLE

[0055] As discussed above, the present invention has particular utilityin a coronary artery bypass graft procedure (CABG), however, the use ofthe instruments of the present invention is now described with regard tothe CABG procedure by way of example only and not to limit the scope orspirit of the present invention. A patient is prepared for cardiacsurgery in a conventional manner using conventional techniques andprocedures. The patient is then anesthetized and ventilated usingconventional techniques. A conventional CABG procedure is performed byharvesting the greater saphenous vein from one or both of the patient'slegs. The surgeon prepares an opening to the heart by dividing thepatient's sternum (conventional median sternotomy) and spreading the ribcage apart using a surgical retractor. The surgeon next beginsdissecting the internal mammary artery (IMA) from the chest wall of thepatient, so that the distal end of the vessel may be anastomosed to thediseased lower anterior descending (LAD) coronary artery on the distalside of a lesion on the septum near the left ventricle of the heart as asource of oxygenated blood. During the surgical procedure, the surgeonoptionally elects to have the patient's heart beating to perform aconventional beating heart CABG, although the surgeon has acardiopulmonary bypass machine (CPB) primed with the patient's blood andavailable if it is necessary to convert the beating heart procedure intoa conventional stopped heart procedure.

[0056] The surgeon prepares the heart for attaching the graft vessels bycutting and pulling away the pericardium. After checking the graftvessels for patency, collateral damage and viability, the surgeonprepares to do the anastomoses necessary to bypass the lesions in thecoronary arteries. The surgeon sutures the proximal end of each graftvessel to the patient's aorta and the distal end to the diseasedcoronary artery, distal to the blockage or lesion. The distal end of theLAD is similarly anatomosed to a coronary artery distal to a lesion in aconventional manner. The surgeon checks the bypass grafts for adequateblood flow in a conventional manner, and then completes the remainder ofthe operation in a conventional manner.

[0057] The veins used in the CABG procedure are harvested endoscopicallyusing the vein harvesting instruments of the present invention. Usingthese instruments, initially the patient's leg is positioned to beslightly bent and is turned to expose the inner leg. A marker is used toshow on the skin the location of the vein to be harvested. Then anincision is created on the inner leg near the knee, through the skin andsubcutaneous layers. The vein typically lies directly beneath thesubcutaneous layers and so a middle portion of the vein is accessedthrough the incision. After some initial dissection with conventionalblunt dissectors around this portion of the vein, a surgical instrumentis introduced into the incision. An endoscope provides visualization ofthe vein and surrounding tissue within the working space inside thehead. The instrument is advanced along the vein. Side branches off ofthe vein are ligated and divided a few millimeters away from the vein,taking great care not to injure the vein in any way. The harvestingprocedure continues in this manner until the vein is hemostaticallyisolated from surrounding tissues and blood supply along the portion tobe harvested. Then stab incisions are created through the skin andsubcutaneous layers at the distal and proximal ends of the vein,ligation clips are applied, and the vessel is transected in order toremove the vein from the knee incision. Thee harvested vein is preparedfor use as grafts in a conventional manner.

[0058] While there has been shown and described what is considered to bepreferred embodiments of the invention, it will, of course, beunderstood that various modifications and changes in form or detailcould readily be made without departing from the spirit of theinvention. It is therefore intended that the invention be not limited tothe exact forms described and illustrated, but should be constructed tocover all modifications that may fall within the scope of the appendedclaims.

What is claimed is:
 1. A surgical device for severing tissue, thesurgical device comprising; a first shaft having a first internal lumenand a first slot disposed at a distal end; a clamp slidingly disposed inthe first slot between open and closed positions to capture tissue inthe first slot, the clamp having a clamping surface disposed at a distalend; at least one electrode for applying RF energy to the tissuecaptured in the first slot; a cutting blade slidingly disposed in thefirst slot between open and closed positions, the cutting blade having acutting edge to sever the tissue; first actuation means for actuatingthe clamp between the open and closed positions; and second actuationmeans for actuating the cutting blade between the open and closedpositions.
 2. The device of claim 1, further comprising a dissection tipdisposed at the distal end of the first shaft for dissecting tissue. 3.The device of claim 1, wherein the first shaft is disposed at a proximalend to a handle.
 4. The device of claim 1, wherein the clamp comprises asecond shaft having a second internal lumen, the second shaft beingslidingly disposed in the first lumen.
 5. The device of claim 4, whereinthe second shaft has a second slot at the distal end, wherein the secondslot divides the clamping surface into two prongs.
 6. The device ofclaim 5, wherein the cutting blade is slidingly disposed in the secondinternal lumen of the second shaft.
 7. The device of claim 6, whereinthe at least one electrode comprises first and second electrodes, eachof a different polarity.
 8. The device of claim 7, wherein the firstelectrode comprises at least the clamping surface of the clamp and thesecond electrode comprises at least the cutting edge of the cuttingblade.
 9. The device of claim 7, wherein the first electrode comprisesat least the clamping surface of the clamp and at least the cutting edgeof the cutting blade and the second electrode comprises at least aportion of the first shaft.
 10. The device of claim 9, wherein the atleast a portion of the first shaft comprises an edge defining the firstslot in the first shaft.
 11. The device of claim 1, wherein the firstactuation means comprises a button movably disposed in a handle andoperatively connected to the clamp, wherein moving the button moves theclamp between the open and closed positions.
 12. The device of claim 1,wherein the second actuation means comprises a button movably disposedin a handle and operatively connected to the cutting blade, whereinmoving the button moves the cutting blade between the open and closedpositions.
 13. The device of claim 1, wherein the first and secondactuation means comprises a button movably disposed in a handle andoperatively connected to the clamp and cutting blade, wherein moving thebutton a first predetermined amount moves the clamp between the open andclosed positions and moving the button a second predetermined amountfurther moves the cutting blade between the open and closed positions.14. The device of claim 1, wherein the tissue is a side branch of avessel being harvested.
 15. A method for severing tissue, the methodcomprising: providing a surgical device comprising; a shaft having anfirst internal lumen and a slot disposed at a distal end; a clampslidingly disposed in the slot between open and closed positions tocapture tissue in the slot, the clamp having a clamping surface disposedat a distal end; at least one electrode for applying RF energy to thetissue captured in the slot; a cutting blade slidingly disposed in theslot between open and closed positions, the cutting blade having acutting edge to sever the tissue; first actuation means for actuatingthe clamp between the open and closed positions; and second actuationmeans for actuating the cutting blade between the open and closedpositions; capturing tissue in the slot; sliding the clamp in the slotto clamp the tissue in the slot; applying RF energy to the at least oneelectrode to cauterize the tissue; sliding the cutting blade in the slotto sever the cauterized tissue.
 16. The method of claim 15, wherein thetissue is a side branch of a vessel to be harvested.
 17. The method ofclaim 16, further comprising dissecting tissue from the vessel to beharvested.
 18. The method of claim 16, wherein the first actuation meanscomprises a button movably disposed in a handle and operativelyconnected to the clamp, the method further comprising moving the buttonto move the clamp between the open and closed positions.
 19. The methodof claim 16, wherein the second actuation means comprises a buttonmovably disposed in a handle and operatively connected to the cuttingblade, the method further comprising moving the button to move thecutting blade between the open and closed positions.
 20. The method ofclaim 16, wherein the first and second actuation means comprises abutton movably disposed in a handle and operatively connected to theclamp and cutting blade, the method further comprising moving the buttona first predetermined amount to move the clamp between the open andclosed positions and moving the button a second predetermined amount tofurther move the cutting blade between the open and closed positions.